Mercury conserving switch



Oct. 6, 1942. .1f H. sTALEY 2,298,178

MERCURY CONSERVING SWITCH Filed 'July 28, 1941 [(0 15. /o 1*/ l l0 14 7 I3 HIV Il l2! n H /Z /Z 4. '4 Z l '2:3 l

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Patented Oct. 6, 1942 UNETED STATES PATENT @EFIQE 4 Claims.

This invention relates to mercury switches of' the type formed -by telescoping metallic members in which mercury is employed to complete .a circuit between those metallic members upon suitable tilting or rocking of the switch. The immediate invention is particularly concerned with a switch of the above indicated nature for use to handle low voltages such as in the ordinary 6-8 voltage system employed in automobiles in the lighting and signaling circuits. Where a mercury switch is employed to handle currents of such low voltage, it is possible toemploy a simplified structure as compared to the structure required for much higher voltages.

It is a primary object of this invention to provide an exceedingly simple .structure which may be operated by use of far less mercury than has heretofore been employed in these types of switches, the conserving of the volume of mer-V cury in each switch being of exceedingly great importance, particularly under war conditions existing at the present time.

A further important object .of the invention resides in the peculiar structure developed to permit the use of the lo-w mercury content and still preserve successful functioning of the switch. These and other important objects and advantages of the invention, such as the new and novel association of the various elements asset forth in the appended claims, Awill become apparent to those versed in the art in the following description of the invention as illustrated` in the .aoco panying drawing, in which Fig. 1 is a View in side elevation of a structure embodying the invention;

Fig. 2, a View 'in central vertical section, wherein the switch is shown in the closed circuit position;

Fig. 3, a view in similar section but inverted to be in an open circuit position in reference to the position shown in Fig. 2';

Fig. 4, a view in cap end elevation; and

Fig. 5, a view in central longitudinal section of a modified form of the invention.

Like characters of reference indicate like parts throughout the several views in the drawing.

Referring to the drawing, a metallic body .I c is formed to have a cylindrical bore II open at one end of the body and closed at the other end. As shown in Figs. 2 and 3, a cylindrical insulating sleeve I2 is telescoped over the body I' from the open end thereof, and in the form herein shown, an end of this sleeve I2 is positioned in abutment with an annular shoulder I3 provided on the body I-Il.

The 'sleeve I2 thus positioned extends axially beyond the open end of the body IE). A metallic cap I4 is formed in the nature of a cup and is telescoped over the extending endv of the eeve l I2 with a pressed fit, the sleeve I2 being of a resilient nature. The cap i4 is forced down over the sleeve I2 a suitable distance to leave an exposed length of the sleeve I2 between the body shoulder I 3 and the rim of the cap i4 directed theretoward. The closed end of the cap l@ is at the same time spaced a distance from the open end of the body It) so as to leave exposed therebetween the extending length of the sleeve I2. In the present form of the invention, the length of the sleeve I2 is proportioned in regard to the lengths of the body IIJ and the cap I to properly position the cap I4 in relation to the body Iii Vwhen the end of the extended length cf the sleeve I2 abuts the inside of the cap end.

The cap I4 is kformed to have a central inwardly extending convex surface I5, herein shown as being formed by centrally pressing inwardly the end of th cap I4 to leave an externally exposed concave cavity VI Such formation 3 of the cap is produced readily by a stamping or .i with the body IllV and the cap id. For example,

in a switch of the above description, Where the internal diameter of the body Ii) is .242 inch and the open end of the body It) is spaced from the inside of the cap I4 a distance of .094 inch, and the internal diameter of the sleeve l2 is .287 inch, there would have to be employed at least two grams of mercury in the absence of the convex area I5. Now by forming that convex surface I5 wherein the depth of the cavity I6 is made to be .022 inch with a Vdiameter of .156 inch (the thickness of the cap 'H being .022 inch), only one-fourth of that amount of mercury is required, namely one-half gram.

In this particular size of switch, the size be ing indicated as only one particular size and not in limitation of the invention, this small amount of mercury, due to its inherent nature, assumes a shape to one side of the axis of the switch as suggested in Fig. 2, the dimensions -in any event of the various parts-being such that whenv ,the

mercury tends to assume its inherent globular shape, it will roll to one side of the cap I4 by reason of the inwardly protruding surface I5, and in so doing will reach and be in substantial contact With the end of the body l0, when the switch is turned to have its axis substantially vertical, as shown in Fig. 2, with the cavity I6 on the under side. Then to break the circuit established by the mercury I1 between the body I and the cap I4, the switch is tilted back to a position which will cause the mercury I1 to flow down into the body I0, the extreme position in this direction of rocking being that shown in Fig. 3 where the switch has been rocked 180 degrees from the position shown in Fig. 2 and where the mercury I1 then rests on the closed end of the body IU.

Referring to the modiiied form of the invention as illustrated in Fig. 5 in the drawing, a body I8 is formed to receive telescopically therewithin by a forced it an insulating sleeve I9. Over the other end of the sleeve I9 is forced a cap to have its rim spaced from the rim of the body I8 to leave an exposed length of the sleeve I9 therebetween. The body I8 is provided with a central outwardly deformed part 2| to leave a concave well 22 on the inside thereof. The cap 20 is provided with a central pin 23 suitably xed thereto to extend axially within the sleeve I9 to be directed toward and to terminate over this well 22. A globule of mercury 24 is provided so that when the Switch in this form is rocked to have the body I8 undermost, this mercury 24 will flow into the well 22 and surround the lower end of the pin 23 and thereby complete a -circuit through the pin 23 between the body I8 and the cap 20. It is therefore to be seen that in this modied form, a very small amount of mercury is employed for the purpose of bridging the two principal metallic members of the switch.

While not necessarily so, the insulating sleeve I2 and I9 in the two forms are employed to have their ends serve as positioning means for the respective metallic bodies and caps telescoping therewith, this feature serving to permit rapid and accurate production of the switches. The fits about the insulating sleeves in each instance are such that Ipassage of gases inwardly or outwardly is to all practical purposes prevented. The exposed area of the insulating sleeve in either case within the switch is of no consequence since under the low voltages for which the switch is designed, there is no arcing that would unduly deteriorate the material. It is to Ibe noted that in the form of the invention shown in Figs. 2 and 3, the cap I4 overlaps the body I0 through the intervening sleeve I2, thereby obtaining a greater structural strength than would be hady in the form shown in Fig. 5 where there is simply an intervening length of the insulating sleeve I9 between the metallic members I8 and 20.

An important advantage of the structure shown in Fig. 5 is that the angle at which the switch is tipped to break the circuit (remove mercury 24 from pin 23) may be varied to meet predetermined conditions or construction of the switch tilting means. That is, by varying the diameter, the depth, or both of the well 22, or by varying the Size of the mercury globule 24, the angle of tilt of the switch required to Ibreak the circuit may be predetermined to be a denite value, such as twenty degrees, thirty degrees, or forty-rive degrees from the vertical.

While the invention has herein been shown and described in a more or less minute detail, itis obvious that structural changes may be employed without departing from the spirit of the invention and I therefore do not desire to be limited to that precise form Ibeyond the limitations as may -be imposed by the following claims.

I claim:

1. In a mercury switch for low voltages, means for conserving the quantity of mercury required per switch comprising a pair of cupped metallic members; one of said members having a central inwardly lprotruding boss defining an annular channel therearound; a cylindrical, open end insulating sleeve; said cupped member having said boss being sealably engaged over an end of said sleeve, and the other cupped member being sealably engaged inside of the sleeve to extend toward the other member to leave an annular gap therebetween; and a quantity of mercury within the closed chamber formed by said cupped members with said sleeve, said mercury quantity being limited to be just suiiicient to bridge said gap at one side of said boss when the switch is turned to have the boss-cupped member undermost.

2. In a mercury switch for low voltages, a metal cup; a second metal cup; a boss extending centrally inwardly from the floor of the second cup; a cylindrical insulating sleeve, both of said cups frictionally telescoping with said sleeve to have the cups form end closures on said sleeve and to have a cylindrical wall of the rst cup extending inside of said sleeve to approach the other cup but to terminate without contact therewith, whereby a cylindrical chamber is formed with metal closures at each end and with a metal wall approximating its length; and a limited quantity of mercury in said chamber, said quantity being limited to that size of an inherently forming globule about one side of said boss when the switch is tilted to have the second cup undermost, the spacing between nearest parts of said cups within said chamber being such as to have said globule bridge thereacross in said tilted position.

3. In a mercury switch for low voltages, a metal cup; a second metal cup; a boss extending centrally inwardly from the iioor of the second cup; a cylindrical insulating sleeve, both of said cups frictionally telescoping with said sleeve to have the cups form end closures on said sleeve and to have a cylindrical wall of the rst cup extending inside of said sleeve to approach the other cup but to terminate without contact therewith, whereby a cylindrical chamber is formed with metal closures at each end and with a metal wall approximating its length; and a limited quantity of -mercury in said chamber, said quantity being limited to that size of an inherently forming globule about the side of said boss when the switch is tilted to have the second cup undermost, the spacing between nearest parts of said cups within said cham-ber being such as to have said globule bridge thereacross in said tilted position, a shoulder on said one cup against which said sleeve abuts, said second cup abutting by its end the other end of said sleeve, whereby the difference in lengths of said sleeve and of said first cup wall determines the gap width between the cups.

4. In a mercury switch for low voltages, a metal cup; a second metal cup; a boss extending centrally inwardly from the iloor of the second cup; a cylindrical insulating sleeve, both of said cups frictionally telescoping with said sleeve to have the cups form end closures on said sleeve and to have a cylindrical Wall of the rst cup ance between said cups within said chamber, and extending inside of said sleeve to approach the the diameter and height of said boss being corother cup but to terminate Vwithout contact thererelated so that said mercury quantity may be with, whereby a cylindrical chamber is formed one-fourth that otherwise required in the absence with metal closures at each end and with a metal 5 of said boss.

Wall approximating its length; and a limited JOSEPH H. STALEY. quantity of mercury in said chamber; the clear- 

